The solid light-emitting device comprising a light-emitting semiconductor element such as a light emitting diode (LED) and a phosphor embedded in a sealant is well known and widely utilized, for example, as a back light of a liquid crystal display and an illumination device. In the solid light-emitting device, the semiconductor element emits a light by supply of electric energy and the phosphor is excited by the light emitted by the semiconductor element to emit a visible light of a wavelength differing from that of the light emitted by the semiconductor element. The light emitted by the semiconductor element generally is a ultraviolet or violet light having a wavelength of 350 to 430 nm. The phosphor may emit a blue light, a green light or a red light upon excitation with the light emitted by the semiconductor element. Also known is a white light-emitting device such as a white light-emitting LED device in which the white light is produced by mixing the blue light, green light and red light altogether.
In the solid light-emitting device, the phosphor is dispersed and embedded in a sealant to form a dispersed phosphor-containing sealant phase. The dispersed phosphor-containing sealant phase can be produced by placing a sealing composition comprising a curable sealing compound and a powdery phosphor over the semiconductor element unit and then curing the sealing compound.
As the sealing compound, a curable silicone resin is well known.
JP 2010-248411 A discloses a curable silicone resin containing an inorganic phosphor pre-treated with a hydroxyalkoxysliane or its oligomer and a light-emitting device in which a semiconductor element (LED chip) is sealed with a cured silicone resin composition containing the pre-treated inorganic phosphor. In this patent publication, it is described that phosphors showing low resistance to humid conditions, such as a sulfate phosphor and a silicate phosphor, are kept stable for a long period of time in a cured silicone resin sealant phase if the phosphors are pre-treated with a hydroxyalkoxysliane or its oligomer.
WO 2010/090280 A1 discloses a transparent sealant composition comprising a polysiloxane modified with an alkoxysilane and a curing catalyst, and a light-emitting semiconductor element sealed with the transparent sealant composition.
WO 2011/125832 A1 discloses an organic-inorganic hybrid prepolymer and a process for production thereof in which the organic-inorganic hybrid prepolymer is prepared by a condensation with hydrolysis of polydimethyl-siloxane having a silanol group on its one end or both ends and an oligomer of an alkoxide of metal and/or semi-metal or its derivative.